81. Are 1-in-10-Year Events Really 1-in-10-Year Events Anymore?

Are 1-in-10-Year Events Really 1-in-10-Year Events Anymore? When evaluating resource adequacy requirements, many power companies and grid operators have used a methodology that originated more than 70 years ago. This probabilistic reliability approach has generally performed adequately through the years. It has generally evaluated loss-of-load events occurring at frequencies of one-day-in-10-years (1-in-10) to be acceptable in terms of system reliability. However, it’s not without risk, as incidents in Texas, California, and other parts of the country and world have demonstrated in recent history. In light of these events, it’s worth asking: have risks changed? It could be that the method used to evaluate what constitutes a 1-in-10 event is no longer sound. “When you have 1-in-a-5 or 1-in-a-10-year event that’s happening every year, most likely those are not 1-in-a-10 or 1-in-100-year events,” Electric Power Research Institute (EPRI) CEO Arshad Mansoor said as a guest on The POWER Podcast. “Really, what we need to go is beyond that. We need to look forward to a future, and not really just back-cast, but forecast. What is the resiliency of the grid that we need when maybe societal dependence on electricity has doubled because of electrification, where extreme weather is becoming frequency, and severity is becoming a norm? And, our resource mix is changing pretty rapidly, and these changes are profound. So, taking all those three trends into consideration, we just need to step back—and resource adequacy is one part of the planning process,” Mansoor said. In rather prescient timing, EPRI published a technical update (or white paper) on Jan. 28—about two weeks before uncharacteristically cold weather caused widespread blackouts all across Texas. “That timing was not by design,” Mansoor said, noting that EPRI has long been working on ways to enhance grid design, planning, and operation to help navigate the energy transition. According to the abstract, “This white paper focuses on planning for resource adequacy give